Field of the Disclosure
The present invention relates to a light emitting device, and more particularly to a light emitting device package configured to improve the quality of light and a lighting apparatus using the same.
Discussion of the Related Art
Light sources, light emitting methods, driving methods, etc. with regard to lighting appliances have been studied, and in recent years, light emitting devices advantageous in terms of efficiency, color diversity, autonomous design, etc. have received attention as a light source of a lighting appliance.
In particular, Light Emitting Diodes (LEDs) are configured to generate light by exciting electrons across a band gap between a conduction band and a valence band of a semiconductor active (light emitting) layer. Electronic transition causes generation of light having a wavelength depending on the size of the band gap. Accordingly, color (wavelength) of light emitted by light emitting diodes varies according to semiconductor materials of an active layer of light emitting diodes.
Meanwhile, color reproduction is measured using a Color Rendering Index (CRI, Ra). The CRI (Ra) is a corrected average value of relative measurement values with regard to color rendition of a lighting system as compared to color rendition of a reference radiator when the lighting system emits light of eight reference colors. That is, this refers to relative shift measurement on a surface color of a subject when a specific lamp emits light.
Light perceived as white is basically a mixture of two or more colors (wavelengths) of light. A single light emitting diode junction configured to generate white light has not yet been developed.
In one example, a white light emitting diode package includes a light emitting diode pixel/cluster of red, green, and blue light emitting diodes, and generates light perceived as white via mixing of red light, green light, and blue light.
In another example, a white light emitting diode package includes a light emitting diode configured to generate green light, and a light emitting material, for example, a fluorescent material, to emit yellow light when excited by light emitted from the light emitting diode. Light perceived as white is generated via mixing of blue light and yellow light.
The above references are incorporated by reference herein where appropriate for appropriate teachings of additional or alternative details, features and/or technical background.